lib/blkid/llseek.c

   1 /*
   2  * llseek.c -- stub calling the llseek system call
   3  *
   4  * Copyright (C) 1994, 1995, 1996, 1997 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the
   8  * GNU Lesser General Public License.
   9  * %End-Header%
  10  */
  11
  12 #define _LARGEFILE_SOURCE
  13 #define _LARGEFILE64_SOURCE
  14
  15 #include "config.h"
  16 #if HAVE_SYS_TYPES_H
  17 #include <sys/types.h>
  18 #endif
  19
  20 #if HAVE_ERRNO_H
  21 #include <errno.h>
  22 #endif
  23 #if HAVE_UNISTD_H
  24 #include <unistd.h>
  25 #endif
  26 #ifdef __MSDOS__
  27 #include <io.h>
  28 #endif
  29
  30 #include "blkidP.h"
  31
  32 #ifdef __linux__
  33
  34 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
  35
  36 #define my_llseek lseek64
  37
  38 #elif defined(HAVE_LLSEEK)
  39 #include <syscall.h>
  40
  41 #ifndef HAVE_LLSEEK_PROTOTYPE
  42 extern long long llseek(int fd, long long offset, int origin);
  43 #endif
  44
  45 #define my_llseek llseek
  46
  47 #else   /* ! HAVE_LLSEEK */
  48
  49 #if SIZEOF_LONG == SIZEOF_LONG_LONG
  50
  51 #define llseek lseek
  52
  53 #else /* SIZEOF_LONG != SIZEOF_LONG_LONG */
  54
  55 #include <linux/unistd.h>
  56
  57 #ifndef __NR__llseek
  58 #define __NR__llseek            140
  59 #endif
  60
  61 #ifndef __i386__
  62 static int _llseek(unsigned int, unsigned long, unsigned long,
  63                    blkid_loff_t *, unsigned int);
  64
  65 static _syscall5(int, _llseek, unsigned int, fd, unsigned long, offset_high,
  66                  unsigned long, offset_low, blkid_loff_t *, result,
  67                  unsigned int, origin)
  68 #endif
  69
  70 static blkid_loff_t my_llseek(int fd, blkid_loff_t offset, int origin)
  71 {
  72         blkid_loff_t result;
  73         int retval;
  74
  75 #ifndef __i386__
  76         retval = _llseek(fd, ((unsigned long long) offset) >> 32,
  77                          ((unsigned long long)offset) & 0xffffffff,
  78                          &result, origin);
  79 #else
  80         retval = syscall(__NR__llseek, fd, ((unsigned long long) offset) >> 32,
  81                          ((unsigned long long)offset) & 0xffffffff,
  82                          &result, origin);
  83 #endif
  84         return (retval == -1 ? (blkid_loff_t) retval : result);
  85 }
  86
  87 #endif  /* __alpha__ || __ia64__ */
  88
  89 #endif /* HAVE_LLSEEK */
  90
  91 blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int whence)
  92 {
  93         blkid_loff_t result;
  94         static int do_compat = 0;
  95
  96         if ((sizeof(off_t) >= sizeof(blkid_loff_t)) ||
  97             (offset < ((blkid_loff_t) 1 << ((sizeof(off_t)*8) -1))))
  98                 return lseek(fd, (off_t) offset, whence);
  99
 100         if (do_compat) {
 101                 errno = EOVERFLOW;
 102                 return -1;
 103         }
 104
 105         result = my_llseek(fd, offset, whence);
 106         if (result == -1 && errno == ENOSYS) {
 107                 /*
 108                  * Just in case this code runs on top of an old kernel
 109                  * which does not support the llseek system call
 110                  */
 111                 do_compat++;
 112                 errno = EOVERFLOW;
 113         }
 114         return result;
 115 }
 116
 117 #else /* !linux */
 118
 119 #ifndef EOVERFLOW
 120 #ifdef EXT2_ET_INVALID_ARGUMENT
 121 #define EOVERFLOW EXT2_ET_INVALID_ARGUMENT
 122 #else
 123 #define EOVERFLOW 112
 124 #endif
 125 #endif
 126
 127 blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int origin)
 128 {
 129 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
 130         return lseek64 (fd, offset, origin);
 131 #else
 132         if ((sizeof(off_t) < sizeof(blkid_loff_t)) &&
 133             (offset >= ((blkid_loff_t) 1 << ((sizeof(off_t)*8) - 1)))) {
 134                 errno = EOVERFLOW;
 135                 return -1;
 136         }
 137         return lseek(fd, (off_t) offset, origin);
 138 #endif
 139 }
 140
 141 #endif  /* linux */
 142
 143